Emulsifier concentrations, effect particle size distributions

Fig 15 Effect of initial emulsifier concentration on particle size distribution(ExperimentaI conditions . 25 g/Z-water, Mo 0,2 g/cc-water )... 

Effect of emulsifier concentration upon particle size distribution ... 

Quasi-elastic light scattering is an excellent technique for studying the formation and stability of submicrometer emulsions. Improvements in the methods of quasi-elastic light scattering data acquisition and analysis that enable full particle-size distribution studies of sub-micrometer emulsion systems are discussed. Using several oil/water emulsion systems as examples, we demonstrate the ability of these techniques to determine the effect of emulsifier concentration on the particle-size distribution produced by an inversion method of emulsification. Some of the benefits of obtaining the full distribution are also discussed. 

The chemical nature and the concentration of an emulsifying agent also play a role in determining the viscosity of emulsions (37). The average particle size, particle size distribution, and the viscosity of the continuous phase (to which an emulsifier is normally added) all depend upon the properties and concentration of emulsifying agent. Also, ionic emulsifiers introduce electroviscous effects, leading to an increase in the emulsion viscosity. 

Two crude oils were used, a California crude with a viscosity of 24 poise at 25 C and a Canadian crude of 164 poise. Both could be emulsified by the addition of NaOH which reacted with the acids present in the crude. A series of oil-in-water emulsions containing 60% (by volume) of oil were prepared. Concentration of NaOH and NaCl and mixer speed were varied. Emulsion stability was measured as was particle size distribution and viscosity and the effect of aging on the latter two. Emulsions of the heavier crude had viscosities about 600 times smaller than the crude viscosity. 

Details are given of a non-steady-state operation for controlling latex particle size distribution by using a continuous emulsion polymerisation of vinyl acetate. The experiment was conducted in a continuously stirred tank reactor under conditions below the critical micelle concentration of the emulsifier. The mean residence time was switched alternately between two values in the nonsteady-state operation to induce oscillations in monomer conversion in time. The effect of the switching operation on particle size distribution is discussed. 13 refs. 

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